Affective deficits have long been considered a prominent feature of schizophrenia. Affective flattening is the only negative symptom included in every major rating scale for the assessment of negative symptoms, and based on a review of research addressing the validity of the distinction between positive and negative symptoms, McGlashan and Fenton (1992) recently suggested that flat affect be included among the defining criteria for schizophrenia in DSM-IV. Given this recognition of the importance of affective deficits in schizophrenia, it is surprising that the characteristics of these symptoms have not been well described. It has recently been argued that current approaches to affective flattening are confounded by the social and neuromotor deficits that are also prevalent in schizophrenia (Dworkin, 1992). If the neurobiological and psychological processes underlying affective deficits are to be understood, approaches for examining affective flattening that are relatively unconfounded by social and neuromotor processes must be developed. The investigation of pain insensitivity in schizophrenia is one such approach to examining affective flattening. Insensitivity to pain has been reported frequently in individuals with schizophrenia, but this phenomenon has never been systematically investigated. The primary aims of the proposed research are to carefully characterize pain insensitivity in schizophrenia and its relationship to affective flattening and to examine the relationships between these two variables and social and neuromotor deficits. This will make it possible to test the hypothesis that pain insensitivity is a manifestation of affective flattening in schizophrenia, one which is relatively independent of social and neuromotor processes. In addition, the data will make it possible to evaluate the extent to which different measures of affective deficits are confounded with social and neuromotor deficits, which will not only lead to greater clarity in the conceptualization of affective flattening in schizophrenia but will also improve the construct validity of approaches to its assessment. The proposed research also has important implications for the welfare of individuals with schizophrenia; numerous clinical reports have suggested that pain insensitivity is very detrimental to health in schizophrenia and can have life-threatening consequences, and pain insensitivity may also account for various self- injurious behaviors that are found in individuals with schizophrenia, including some aspects of the behavior of homeless schizophrenics. A more complete characterization of pain insensitivity and affective flattening in schizophrenia will not only facilitate the investigation of their underlying neurobiological and psychological processes, but should also make it possible to develop more effective methods for ameliorating these important symptoms and their negative consequences for the health and well-being of individuals with schizophrenia.